Benefit of New High-Precision LLR Data for the Determination of Relativistic Parameters

Since 1969, Lunar Laser Ranging (LLR) data have been collected by various observatories and analysed by different analysis groups. In the recent years, observations with bigger telescopes (APOLLO) and at infra-red wavelength (OCA) are carried out, resulting in a better distribution of precise LLR data over the lunar orbit and the observed retro-reflectors on the Moon. This is a great advantage for various investigations in the LLR analysis. The aim of this study is to evaluate the benefit of the new LLR data for the determination of relativistic parameters. Here, we show current results for relativistic parameters like a possible temporal variation of the gravitational constant G/G(0) = (-5.0 +/- 9.6)x10(-15)yr(-1), the equivalence principle with Delta(m(g)/m(i))(EM)=(-2.1 +/- 2.4)x10(-14), and the PPN parameters beta-1=(6.2 +/- 7.2)x10(-5) and gamma-1=(1.7 +/- 1.6)x10(-4). The results show a significant improvement in the accuracy of the various parameters, mainly due to better coverage of the lunar orbit, better distribution of measurements over the lunar retro-reflectors, and last but not least, higher accuracy of the data. Within the estimated accuracies, no violation of Einstein's theory is found and the results set improved limits for the different effects.

Automated summary

The Lunar Laser Ranging (LLR) data collected since 1969 have seen improvements in accuracy and distribution thanks to observations with bigger telescopes and at infra-red wavelength. This has led to better coverage of the lunar orbit and retro-reflectors, resulting in significant improvements in the determination of relativistic parameters. No violation of Einstein's theory was found within the estimated accuracies, and the results have set improved limits for the different effects.